A number of medical imaging techniques are used heavily in the provision of spatially resolved information on disease and physiological status and accordingly play a critical role in clinical diagnostics and subsequent treatment. Though, for most imaging modes, contrast is potentially enhanced through the use of contrast agents or improved hardware or imaging protocols, no single methodology provides, in isolation, a detailed mapping of anatomy, disease markers or physiological status. In recent years, the concept of complementing the strengths of one imaging modality with those of another has come to the fore and been further bolstered by the development of fused instruments such as PET/CT and PET/MRI stations. Coupled with the continual development in imaging hardware has been a surge in reports of contrast agents bearing multiple functionality, potentially providing not only a powerful and highly sensitised means of co-localising physiological/disease status and anatomy, but also the tracking and delineation of multiple markers and indeed subsequent or simultaneous highly localized therapy ("theragnostics").